Have a plumbing problem. Made some modifications to hot water copper pipes
in basement, then refilled with water, well found a couple of leaks...so had
to drain whole system again and made repairs..before I refilled with water I
filled with air at 30lb pressure..seemed to be ok so let air out and
refilled again and still have one very small leak...this is on a 1" T
fitting that I had very hard time getting to because of location...the T
fitting seems to be just a shade bigger than the 1" copper pipe I am
soldering into it...one side that I have not touched does not leak..whoever
soldered that side seems like they kind of soldered in a way to build up
solder along edge of joint..and so no leak there...anyway I have just
repaired again and have pressurized with air at 30lbs pressure and once
again can not find any leak...but I am afraid I will refill with water and
get pressure up and find same leak again.

couple of questions....

1. is there some liquid I can place over repair that would help to detect
pinhole leak?

2. if there is still leak how can I solder so as to build up solder on edge
and make better connection?